Odd triplet superconductivity in superconductor ferromagnet hybrid structures

We study the proximity effect in diffusive superconductor-ferromagnet structures. In particular we show that a triplet component of the condensate appears. This component is an odd function of the Matsubara frequency and an even function of the momentum. Therefore it is insensitive to the scattering by non-magnetic impurities. If the exchange field of the ferromagnet is homogeneous in space, only the triplet component with spin projection S=0 appears. The latter penetrates into the ferromagnet over the short length ξ=√{D/h} ( D is the diffusion coefficient and h the exchange field) like the singlet component. However, if the exchange is not homogeneous the condensate has also the components with projections S=±1. These are long-range components which penetrate the ferromagnet over the ξ=√{D/T} ( T is the temperature). We propose some experiments in order to detect the odd triplet component. To cite this article: F.S. Bergeret et al., C. R. Physique 7 (2006).